There are many examples of surgical staplers which deliver staples one at a time. Most of these deliver traditional metal staples which rely on the strength of the staple to pierce the tissue and to hold the tissue surfaces together. Hence the typical surgical stapler engages the first staple at the front of a linear array of staples, and pushes it into the tissue while bending it over an anvil. Once the staple is bent into position, the tissue surfaces that are being held cannot un-bend the metal staple. One of the disadvantages of the metal staple is that it must have a portion that remains exposed through the skin surface in order to allow a medical professional to remove the fastener once biological healing is complete. This exposed portion is unsightly, and the puncture points where the fastener enters the skin, have a risk of infection.
To address the disadvantages of metal staples, various inventors have proposed fasteners made of bioabsorbable materials which can be placed below the surface of the skin. This subcuticular skin closure avoids punctures through the epidermis, and does not require follow-up removal of the staples. Such a fastener is described in U.S. Pat. No. 6,726,705 to Peterson et al, as a “Mechanical Method and Apparatus for Bilateral Tissue Fastening”. A product based on this patent, the INSORB® Subcuticular Skin Stapler, has been commercialized by Incisive Surgical of Plymouth, Minn. The fastener deployed by the INSORB device is significantly thicker in cross section than a metal staple to enable the plastic material to be strong enough to maintain the traditional “U” shape of a staple during the healing process. This added bulk is undesirable as it takes longer to be absorbed by the body. Also the head of the INSORB stapler must be inserted within the incision to deploy the fastener. This means that the user has poor visibility as to the placement of the fastener and that the device cannot be used on small incisions such as those employed in increasingly popular minimally invasive surgery.